Immune checkpoint inhibitors (ICIs) targeting the programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) have revolutionized the treatment landscape for a wide range of cancers, demonstrating significant efficacy and favorable responses and pioneering a new therapeutic paradigm for many types of solid tumors (Ribas and Wolchok, 2018; Tang et al., 2018). Here, PDCD1 is linked to cancer.